1. Field of the Invention
The invention relates to an air outlet arrangement for air screen installations.
2. The Prior Art
Air screen (or air veil) installations are increasingly employed for screening room areas against penetrating external air or against the outflow of room air. In order to achieve energy saving yet efficient screening of the air, the screens (or veils) of air have to exit from the installation in a relatively highly focused and directed manner. This requirement is satisfied by slot outlets. However, slot outlets have the drawback that they generate a relatively strong noise as the air is flowing out. Avoiding outflow noise is deemed desirable especially for air screening installations in work or public areas.
German utility model DE 89 14 343 U1 proposes a sound absorber for the pressure side of air screening installations. This sound absorber comprises a housing with a chamber lined with a sound absorbing material, and air inlet and air outlet openings arranged at right angles in relation to each other. A sound-absorbing, profiled body is arranged within the zone where the flow of air is reversed. The profiled body is tapered in the direction of air flow and extends over the entire width of the chamber. It has a cross section substantially in the form of a streamlined body.
The high technical manufacturing expenditure and the high costs associated therewith for the sound-absorbing lining of the housing have adverse effects in conjunction with the sound absorber. Furthermore, the arrangement of the profiled body where the flow of air is reversed leads to turbulence that reduces the degree of efficiency of such an air screen installation.
It is therefore an object of the invention to reduce the emission of noise in an air screen installation without raising the manufacturing and/or installation expenditures, and without impairing the degree of efficiency of the installation.
This object is accomplished by a slot-shaped outlet arrangement having first flow guide means extending in the interior space of a flow chamber. The flow guide means are extensions of the parallel arranged longitudinal side flanks of the slot outlet, which extend from the outside to the inside. The flow guide means are first parallel with each other, and subsequently extend in a curved manner, diverging from each other, with their free longitudinal edges resting closely against the inner surface of the flow chamber. There are second flow guide means arranged parallel with each other between the longitudinal side flanks transversely in relation to the longitudinal direction.
The flow chamber is connected with the pressure side of a ventilator or other device having the same effect as a ventilator. This way, the driven flow of air is capable of exiting from the slot outlet via the flow chamber with distribution of the air flow over the entire width or height of the area to be screened. This generates an at least substantially axial flow of air in the flow chamber, which is then radially deflected at the slot outlet and forms the screen or veil of air after it exits from the flow chamber.
The design of the slot outlet as defined by the invention, with the transition from the inner surface of the flow chamber formed by the close abutment of the free longitudinal edges of the extended longitudinal side flanks of the slot outlet on the inner surface of the flow chamber, and the curved design of the extended longitudinal side flanks of the slot outlet up to their parallel arrangement at the outlet, prevents eddying of the air flow within the course of its reversal from the axial into the radial direction. This prevents the generation of air flow noise of air screens that are blown out from the slot with a speed of at least up to 20 msxe2x88x921, or at least greatly reduces the generation of such air flow noise. The second flow guide means, which are arranged parallel with each other between the longitudinal side flanks transversely to the longitudinal direction, subdivide the slot outlet in a multitude of blow chambers. This produces a flow of the air screen that is aligned with the angle of the second flow means in relation to the axial flow in the blow chamber. The second flow means are preferably arranged at right angles with respect to the axis of the blow chamber. The blow chambers are designed with at least substantially equally long edges, and with an inward length of the slot outlet, which is where the extended longitudinal side flanks extend parallel in the direction of flow upstream of the second flow guide means, that corresponds at least with the width of the gap of the slot outlet.